Arc welding machines are very well known in the prior art and they usually comprise two different types of units, namely, motor-generator type welding machines and transformer type welding machines, both types having very well defined fields of application. The motor-generator type machines are normally utilized for producing very high amperage welding currents, such as 300 amps or more, which are useful when structural metal parts are to be welded to each other with a very high strength, or when a high penetration of the welding metal is required in the work piece. The transformer type machines, on the contrary, are normally utilized for producing electric welding currents of lower intensity, of the type useful in a blacksmith's shop or when the welding metal does not require a high penetration, whereby said types of machines have specific fields of application for which they have proven to be highly efficient.
Particularly referring to the transformer type prior art arc welding machines, which have been used with good efficiency in blacksmith's shop activities or in structures that do not require a high strength, said machines, while showing a performance and efficiency which is reasonably acceptable, present the serious drawback that, as they require a transformer for the single phase current to reduce the voltage and increase the amperage thereof, they also require large amounts of coil wire, as well as very bulky and heavy iron gaps to contain the primary and the secondary windings of the transformer, which produces a very heavey unit that must be mounted in a sufficiently strong housing to support such a weight. Also, this type of transformer type arc welding machine is required to contain within the housing supporting the transformer, a considerable volume of a cooling dielectric liquid, which renders the machine very costly and heavy and presents serious inconveniences for the transportation thereof, regardless of the fact that said machines are considered as portable machines, and are used very widely in blacksmith's shops.
Another serious inconvenience of the transformer type arc welding machine is that, as the cooling dielectric liquid is relatively costly, it is always necessary to load the machine, that is, the receptacle thereof, with a suitable volume of said liquid, which increases initial cost and also considerably increases the dead weight of the machine, that must be necessarily transported from one place to the other with the liquid within the same, inasmuch as said liquid is not easily available and must be acquired in specialized places.
Therefore, it has long been desired to design an arc welding machine that, is highly efficient for use in blacksmith's shops and also for producing welding cords of the same type produced by the transformer type welding machines, but will not have the serious drawbacks and the cumbersome inconveniences of the latter, and have a light-weight and an easy handling property that was not possible with the prior art transformer type arc welding machines.